Light-emitting diodes (LEDs) can be more effective if an LED package is adequately designed to effectively extract the light which is generated inside the LED under operating conditions. From the perspective of a device designer, effective light extraction can be a matter of improving the chances that light from the LED dies is effectively guided so it can leave the LED package in the desired direction. A number of design features can influence the optical paths such as the orientation and the position of reflective interfaces and whether the type of reflection has a specular or diffuse nature. Moreover, refractive properties of an LED package can affect the efficiency of the light extraction. A number of publications describe how to design LED packages including factors such as structure and composition, for example.
PCT Application Publication No. WO 2005/067063 describes an arrangement comprising a substrate with a plurality of electrically conductive traces and at least one light emitting device surface mounted on the substrate and connected with a first and a second electrical electrode to the electrically conductive traces. A ring that is placed onto the substrate surrounding the light emitting device and comprises a lower surface that is attached to the substrate and an upper surface that is designed to reflect the light emitted by the light emitting device in a desired direction. This ring enables the collection and redirection of light and can allow precise placement of an encapsulation or a lens that may be part of the encapsulation and absorbs thermal energy from the encapsulation that has been transferred from the top and sidewalls of the light emitting device.
U.S. Pat. No. 6,940,704 describes a light-emitting diode comprising a surface mount package having a metal lead frame having mass sufficient to provide low thermal resistance, at least one anode contact pad and at least one cathode contact pad. The LED also includes a reflector positioned within the package, a semiconductor die and an optional focusing dome. The semiconductor die comprises a transparent substrate and a semiconductor component and is positioned within the package so that the semiconductor component and the substrate are arranged side-by-side over the reflector or the die is positioned within the package so that the substrate is on top of the semiconductor component.
U.S. Pat. No. 6,982,522 describes a LED device comprising a base having a recess with the upper surface opened, the inner wall surface of the recess constituting a reflection surface; a LED chip disposed on the inner bottom of the recess; a resin filled in the recess, the resin including phosphors which absorb a part of the light emitted from the LED chip to convert and emit light; and a phosphor layer formed on the reflection surface, the phosphor layer including the phosphors.
U.S. Pat. No. 6,949,771 describes light source including a planar substrate with a centrally positioned aperture. A light emitting diode is mounted on a metallic layer covering the bottom of the aperture and is encapsulated by a transparent encapsulation material. The metallic layer provides a thermal path for heat generated by the light emitting diode.
U.S. Pat. Nos. 6,590,235 and 6,204,523 describe a LED component with light emission in the green-to-near UV wavelength range. The light-emitting semiconductor die is encapsulated with one or more silicone compounds, including a hard outer shell, an interior gel or resilient layer, or both. The silicone material is stable over temperature and humidity ranges, and over exposure to ambient UV radiation.
U.S. Pat. No. 6,995,402 describes a mount for a semiconductor light emitting device which includes an integrated reflector cup. The reflector cup includes a wall formed on the mount which is shaped and positioned to reflect side light emitted from the light emitting device along a vertical axis of the device/mount combination.
U.S. Pat. No. 6,897,486 describes a light-emitting die package and a method of making it. The die package includes a stem substrate having grooves, a wire lead attached to the grooves, and a LED mounted on the stem substrate. Coupled to the substrate are a sleeve, a reflector, and a lens. To make the light-emitting die package, a long substrate is formed and wire leads are attached to the substrate. The substrate including the attached wire leads is cut to predetermined lengths to form individual stem substrates. To each stem substrate, LED, reflector, and lens are coupled.
U.S. Pat. No. 6,610,563 describes a method for producing a surface mounting optoelectronic component comprising the following steps: readying a base body with the optoelectronic transmitter and/or receiver arranged in a recess of the base body, filling the recess of the base body with a transparent, curable casting compound, and placing the optical device onto the base body, so whereby the optical device comes into contact with the casting compound.
United States Patent Application Publication No. 2005/0221519 describes methods of packaging a semiconductor light emitting device which include dispensing a first quantity of encapsulation material into a cavity including the light emitting device. The first quantity of encapsulation material in the cavity is treated to form a hardened upper surface having a selected shape. A luminescent conversion element is provided on the upper surface of the treated first quantity of encapsulation material. The luminescent conversion element includes a wavelength conversion material and has a thickness at a middle region of the cavity greater than proximate a sidewall of the cavity.
United States Patent Application Publication No. 2005/0269587 describes a light-emitting die package and a method of manufacture. The die package includes a lead frame, at least one LED, a moulded body, and a lens. The lead frame includes a plurality of leads and has a top side and a bottom side. A portion of the lead frame defines a mounting pad. The LED device is mounted on the mounting pad. The moulded body is integrated with portions of the lead frame and defines an opening on the top side of the lead frame, the opening surrounding the mounting pad. The moulded body further includes latches on the bottom side of the lead frame. The lens is coupled to the moulded body. A composite lens is used as both reflector and imaging tool to collect and direct light emitted by LED(s) for desired spectral and luminous performance.
United States Patent Application Publication No. 2005/0199884 describes a high-power LED package, in which substantially planar first and second lead frames made of high reflectivity metal are spaced from each other for a predetermined gap. An LED chip is seated on at least one of the lead frames and has terminals electrically connected to the lead frames. A package body made of resin seals the LED chip while fixedly securing the lead frame in its bottom. An encapsulation material fills up the gap between the first and second lead frames.
United States Patent Application Publication No. 2005/0045904 describes a light emitting diode with high heat dissipation which includes a printed circuit board, a conductive material, a LED chip, and a compound resin. The printed circuit board has an upper surface and a lower surface opposite to the upper surface. A via hole penetrated from the upper surface to the lower of the printed circuit board. The upper surface of the printed circuit board is formed with electrodes. The conductive material is filled into the via hole of the printed circuit board. The LED chip is mounted on the upper surface of the printed circuit board and contacts the conductive material. The compound resin encapsulates the LED chip.
United States Patent Application Publication No. 2004/0041222 describes a light-emitting die package which includes a substrate, a reflector plate, and a lens. The substrate is made from thermally conductive but electrically insulating material. The substrate has traces for connecting an external electrical power source to a LED at a mounting pad. The reflector plate is coupled to the substrate and substantially surrounds the mounting pad. The lens is free to move relative to the reflector plate and is capable of being raised or lowered by the encapsulation material that wets and adheres to it and is placed at an optimal distance from the LED chip(s). The lens can be coated with any optical system of chemical that affects the performance of the device.
European Patent No. 1,453,107 describes a LED light comprising a light-emitting device provided to power supply means, encapsulating means for encapsulating the light-emitting device with a light-transmitting material, a reflective surface for reflecting the light emitted from the light-emitting device to a direction perpendicular to the center axis of the light-emitting device or at a large angle to the center axis, opposed to the light-emitting surface of the light-emitting device, a light-emitting diode having a side directing surface for directing sideways the light reflected from the reflective surface to a direction perpendicular to the center axis of the light-emitting device or at a large angle to the center axis, and a reflecting mirror disposed around the light-emitting diode.
Today's typical LED packages require many components with complex mechanical setup or difficult manufacturing in order to realize an accurately performing optical setup. In addition, the LEDs of a package are typically encapsulated with an encapsulation material prior to the mounting of an optical lens which encloses the LEDs. This configuration may result in an undesired amount of encapsulation material being used, for example too much or too little and may result in an impairment of the optical efficiency of the LED package. Therefore there is a need for a new lighting device package.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.